Accuracy of clinical diagnosis and malaria rapid diagnostic test and its influence on the management of children with fever under reduced malaria burden in Misungwi district, Mwanza Tanzania

The in-vivo dynamics of Plasmodium falciparum HRP2: implications for the use of rapid diagnostic tests in malaria elimination

Background

Rapid diagnostic tests (RDTs) that rely on the detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) have become key tools for diagnosing P. falciparum infection. The utility of RDTs can be limited by PfHRP2 persistence, however it can be a potential benefit in low transmission settings where detection of persistent PfHRP2 using newer ultra-sensitive PfHRP2 based RDTs can serve as a surveillance tool to identify recent exposure. Better understanding of the dynamics of PfHRP2 over the course of a malaria infection can inform optimal use of RDTs.

Methods

A previously published mathematical model was refined to mimic the production and decay of PfHRP2 during a malaria infection. Data from 15 individuals from volunteer infection studies were used to update the original model and estimate key model parameters. The refined model was applied to a cohort of patients from Namibia who received treatment for clinical malaria infection for whom longitudinal PfHRP2 concentrations were measured.

Results

The refinement of the PfHRP2 dynamic model indicated that in malaria naïve hosts, P. falciparum parasites of the 3D7 strain produce 33.6 × 10⁻¹⁵ g (95% CI 25.0–42.1 × 10⁻¹⁵ g) of PfHRP2 in vivo per parasite replication cycle, with an elimination half-life of 1.67 days (95% CI 1.11–3.40 days). The refined model included these updated parameters and incorporated individualized body fluid volume calculations, which improved predictive accuracy when compared to the original model. The performance of the model in predicting clearance of PfHRP2 post treatment in clinical samples from six adults with P. falciparum infection in Namibia improved when using a longer elimination half-life of 4.5 days, with 14% to 67% of observations for each individual within the predicted range.

Conclusions

The updated mathematical model can predict the growth and clearance of PfHRP2 during the production and decay of a mono-infection with P. falciparum, increasing the understanding of PfHRP2 antigen dynamics. This model can guide the optimal use of PfHRP2-based RDTs for reliable diagnosis of P. falciparum infection and re-infection in endemic settings, but also for malaria surveillance and elimination programmes in low transmission areas.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04245-z.

Extensive Antibiotic and Antimalarial Prescription Rate among Children with Acute Febrile Diseases in the Lake Victoria Region, Tanzania

OBJECTIVES

Acute mosquito-borne febrile diseases pose a threat to children in the Sub-Saharan-Africa with ∼272 000 children dying worldwide from malaria in 2018. Although the awareness for malaria in this area has increased due to improved health education, the apparent decline of actual malaria cases has not affected clinical practice significantly. This study collected clinical and epidemiologic data of children presenting with acute febrile diseases in order delineate their diagnostic and therapeutic management.

METHODS

A hospital-based cross-sectional clinical study was conducted at the Sekou Toure Regional Referral Hospital in Tanzania. Children between 1 month and 12 years of age with an axillary temperature ≥ 37.5°C were recruited from August 2016 to December 2016. Children received full clinical examination. In addition, file data about diagnostics and treatment were collected and malaria rapid diagnostic tests (mRDTs) were performed. Confirmatory malaria polymerase chain reaction was performed from dry blood spots.

RESULTS

From 1381 children presented in the pediatric outpatient department, 133 met the inclusion criteria. Out of 133 febrile children, 10.5% were malaria positive. Treatment data indicate the prescription of antimalarials in 35.3% and antibiotics in 63.9% of the children with an overlap of 24.1% receiving both. Despite a negative mRDT, 36 patients received antimalarials.

CONCLUSIONS

The findings of this study confirm a significant decline of malaria cases in the Lake Victoria region. The discrepancy between the valuable results provided by mRDTs and the high prescription rates of antibiotics and antimalarials call for an enforced diagnostic and therapeutic algorithm.

LAY SUMMARY

The aim of the study was to take a closer look at reported cases of febrile diseases in the Lake Victoria region and assess the relationship between clinical as well as diagnostic findings and the resulting therapeutic concept. Based on these findings the prescription rate of antimalarial and antibiotic drugs was analyzed. The results showed an overall high prescription rate of antimalarials and antibiotics in both diagnosed malaria cases and cases with diagnosed bacterial infections.Not only with regards to the possible side effects of these medications but also keeping in mind the apparent misuse of resources this practice poses a serious burden to the health care system in this low resource country.

The effect of malaria rapid diagnostic tests results on antimicrobial prescription practices of health care workers in Burkina Faso

BACKGROUND

Malaria rapid diagnostic tests (RDT) are widely used in endemic areas in order to comply with the recommendation that malaria treatment should only be given after the clinical diagnosis has been confirmed by RDT or microscopy. However, the overestimation of malaria infection with the use of PfHRP2 based RDT, makes the management of febrile illnesses more challenging. This study aimed to assess the effect of the use of malaria RDT on antimicrobial prescription practices.

METHODS

A prospective study was conducted among febrile children under-5 years of age attending four health facilities and the referral hospital in the Nanoro Health District (Burkina Faso). To assess the effect of malaria RDT testing on the prescriptions of antimicrobials in febrile children, the initial diagnosis and antimicrobial prescriptions following a malaria RDT testing were recorded. The necessity of these prescriptions was subsequently checked by assessing the actual cause of fever by expert malaria microscopy and a microbiology analysis of blood, urine, stool and nasopharynx swabs that were collected from febrile cases to determine the actual cause of the fever episode.

RESULTS

Malaria was diagnosed by nurses, who are the primary health care providers, with a malaria RDT in 72.7% (798/1098) of febrile children, but only 53.7% (589/1097) cases could be confirmed by expert microscopy. Health care workers were likely to prescribe antimalarials to malaria positive RDT compared to malaria negative RDT (RR = 7.74, p = 0.00001). Malaria negative RDT result had a significant influence on the antibiotic prescriptions (RR = 3.57, p = 0.0001). The risk of prescribing antimicrobials was higher in health facility level compared to referral hospital. By cross-checking of laboratory findings to antimicrobial prescriptions, an important part of children with positive bacterial infection have received antibiotic prescriptions although the majority without any infection have also received antibiotics.

CONCLUSION

Despite the good attitude of health care workers to adhere to diagnostic test results, antimalarials and antibiotics remain inappropriate prescribed to febrile children. The low specificity of malaria RDT used could be an important cause of these practices.